Carbs d@#m pos!!

[GLoweVA]

How do you know FOR SURE a float is good?

I read in the tech section there's a way to hook up some tubing to the bowl drain to see what the level is in the bowl. I think this might be the most for sure way to see if the float is indeed floating at the proper level.

I'm assuming because you have brass floats that it's your '79 that you're having issues with. I've got an 80, so I can't offer you too much advice other than don't give up.

Don't let the machine win.

Man created machine, therefore man is smarter than machine.

You can do it!

[81xsproject]

Submerge them in very hot (but not boiling) water. The air inside will heat up and become pressurized. If any have holes, bubbles will come out. Other than that, they should be dent free.

[XS1100_OEM4ME]

Hot water

Submerge them in very hot (but not boiling) water. The air inside will heat up and become pressurized. If any have holes, bubbles will come out. Other than that, they should be dent free.

I like that, the heat expands the air inside, instant pressure, bubbles from ANY leak, mark leak with sharpie, fix and re-test Hey, if Iam in hot water they might as well be also I don't plan on giving up, the beast WILL NOT BEAT ME I just got done repainting the tank and sidecovers gloss black and clear coat, then a good rubb with 3M compound and this carb thing is keeping me from being DONE and being a happy father Thanks for all the tips, now I just have to get over this hang-over and the 4 days of rain we are getting, gave up drinking months ago (I thought

[TopCatGr58]

Hey OEM,

I recently had a problem with my carbs getting gummed up over the summer because I forgot to put in SeaFoam, and parked it too long! The wouldn't take any throttle over choked idle!! Tore them down, cleaned them thoroughly....BTW, in your description you didn't mention the main jet needle = emulsion tube...removing it from inside the carb pushing it out from the bowl side up thru the vacuum slide section? It has several small holes that also need to be cleaned and open. Then I had a BRAIN FART, and set the floats(81 plastic series) which are set to 23mm, but I used the wrong part of the float...the hump distant from the hinge...not the hump right at the hinge, and this resulted in a too low fuel level...and so even though they were properly cleaned, they still behaved badly not taking any throttle input.

Took them off/apart and re-reset the floats to the true proper height.. amazing how 1-2mm's can make such a difference!

So...as stated, almost boiling bubble test, and then the right height, but sounds like you might want to aim/try closer to the 25.0 height.

The proper pilot jets also as stated, the BS series has the metering orifice near the pointy tip, the VM has it near the threaded end, it's this moreso than the side holes that makes the difference..but as stated the VM's usually result in overly rich condition. Like Phil said, sounds like you don't have enough fuel in the bowls. The "choke" jet is in the bottom of the bowl, so it can work with very little fuel in the bowl, but the pilot jet gets it's supply from the main jet, so the fuel level needs to be high enough to feed the main jet and thereby the pilot jet.

Keep at it, and hang in there! T.C.

[XS1100_OEM4ME]

Thanks

Hey OEM,

I recently had a problem with my carbs getting gummed up over the summer because I forgot to put in SeaFoam, and parked it too long! The wouldn't take any throttle over choked idle!! Tore them down, cleaned them thoroughly....BTW, in your description you didn't mention the main jet needle = emulsion tube...removing it from inside the carb pushing it out from the bowl side up thru the vacuum slide section? It has several small holes that also need to be cleaned and open. Then I had a BRAIN FART, and set the floats(81 plastic series) which are set to 23mm, but I used the wrong part of the float...the hump distant from the hinge...not the hump right at the hinge, and this resulted in a too low fuel level...and so even though they were properly cleaned, they still behaved badly not taking any throttle input.

Took them off/apart and re-reset the floats to the true proper height.. amazing how 1-2mm's can make such a difference!

So...as stated, almost boiling bubble test, and then the right height, but sounds like you might want to aim/try closer to the 25.0 height.

The proper pilot jets also as stated, the BS series has the metering orifice near the pointy tip, the VM has it near the threaded end, it's this moreso than the side holes that makes the difference..but as stated the VM's usually result in overly rich condition. Like Phil said, sounds like you don't have enough fuel in the bowls. The "choke" jet is in the bottom of the bowl, so it can work with very little fuel in the bowl, but the pilot jet gets it's supply from the main jet, so the fuel level needs to be high enough to feed the main jet and thereby the pilot jet.

Keep at it, and hang in there! T.C.

Thanks, I am going to work on the floats and needles valves as the gas running out of the carbs and down the motor and, of course into the cyls and causing all kinds of stuff these carbs with the jets and parts that are in them now worked fine a few months ago, pulled them to move the main jet needle to the mid position as it was set to the most rich c-clip spot, it had a flat spot in exceleration from 2000 to 3500 rpm and was told the main jet was to rich causing it

[TopCatGr58]

Hmmm,

I'm no carb guru, but if they were working "alright" in the most rich slide needle clip position...which causes the carbs to get into the mains much sooner, it could have actually been masking an overly LEAN condition, since setting it to the middle position is causing LEAN type symptoms? The pilot circuit may still be clogged. When you pull the MAIN JET Emulsion tube out, check out the hole in the side/end where the main jet screws into it, that hole may be clogged, along with the hole/tunnel between the pilot and main jet towers!? That could also cause the poor low rpm response since it would not be getting any fuel thru the pilot circuit, and that the max RICH needle position may have been the PO's attempt to correct the problem???

See this photo from the tech tips, it shows the hole in the screw end of the emulsion tube that allows the fuel to flow thru the main jet thru the tunnel and into the pilot jet, where it can then flow thru the pilot (low rpm) circuit.



Just some more thoughts trying to help trouble shoot this low rpm problem.
T.C.

PS, flooding carb will also cause poor low rpm response, even just one carb.! I had a broken float post, and when it caused the #2 carb to flood, I could not get any decent low rpm response, it was either idle or WOT, and not much in between, so yes, you need to fix the flooding/leaking float valve problem also.

[BigDick]

What rpms is it turning when you have it idling on full choke? I'm half wondering if your idle stop is turned out too much making the idle too low when the choke is off. IIRC mine idles around 2000-2500 when warmed up on full choke.

[XS1100_OEM4ME]

Idle

What rpms is it turning when you have it idling on full choke? I'm half wondering if your idle stop is turned out too much making the idle too low when the choke is off. IIRC mine idles around 2000-2500 when warmed up on full choke.

That is what mine used to idle at 2500, now it was hitting 5000 rpm, I found all the old jets / parts, will tear down again and find out why fuel is overflowing, this has happened before with these, might be bad float or needle valve, will find out and bench test the crap out of it before re-install

[DGXSER]

You probably already know this, bt since Prom no longer hangs out here, I'll pass on his bench test.

1. With carbs upside down on the bench, hook up a fuel source hung above the carbs. Now "blip" the float to let just a touch of gas through and the air out of the lines. Clean up the fuel with compressed air or paper towel..etc. Leave fuel on to carbs and go make a sandwich. Eat said sandwich. Now go back and check if any fuel at all has leaked through or around the float valves. IF yes, then you obviously have some work to do, if no, go to test two.

2. Set fully assembled carbs up flat and level, just like hanging on the bike on centestand. Re-connect fuel source to carbs. Let the float bowls fill, and see the valves shut off. This will verify that the floats are floating and shuttign off the fuel. Again, if any leaks, you have work to do, if no leaks, hang them on the bike.

This should eliminate the leaking floats, well, it will lessen the chances considerably. First set I worked on I changed fuel lines as well as rebuilt the carbs. Well, I used automotive fuel line with the soft rubber inner lining. The rubber chafed off on the barbs of the Ts in the system and that small parts of rubber were enough to keep a float from sealing. Dang things leaked over and over and over and never the same carb twice in a row. Finally changed fuel line and never had a problem since.

[BigDick]

That is what mine used to idle at 2500, now it was hitting 5000 rpm, I found all the old jets / parts, will tear down again and find out why fuel is overflowing, this has happened before with these, might be bad float or needle valve, will find out and bench test the crap out of it before re-install

5k is way too high, check the little tab that sets how far down your floats can drop. If they're going down too low the needle can get cocked sideways and let boatloads of fuel past which in turn can cause your idle to spike like that. Also if you have everything hooked up and they're leaking fuel out the airbox try tapping the float bowls with a hammer handle or screwdriver handle. After that they'll likely never overflow again. . .

[XS1100_OEM4ME]

Needle valves?

I read on here that some of you have changed your stock fuel float needle valves to a type that has a rubber like tip? What ones would work in a stock 1979 XS1100 Special carb set-up, and were is the best place to order them? Are they a big improvment and worth the $$$, I have had over flow more then once with these carbs Thanks

[3Phase]

Here's Toolmaker Tim's thread about finding and installing some XV920 float valves. It was started November 2010 and has stayed 'alive' to September 2011:-

XV920 Float Valve Mod

[XS1100_OEM4ME]

?

Is this what I need for a 1979 xs1100 special? And what composit floats will replace the brass ones

http://www.z1enterprises.com/Float-N...J750-2560.aspx

[bikerphil]

Are your brass floats no good? As for your needle/seats, I thought you put new units in. I have found that on the 78-9 carbs, keeping everything stock with the exception of pilot/main jet sizes works the best, JMHO.

[XS1100_OEM4ME]

Yes

Are your brass floats no good? As for your needle/seats, I thought you put new units in.

Yes, I put in new fuel needles and seats from my K&L kits, still got gas flowing out the carbs and into the motor, Floats set exact, checked for float leaks, none detected, just gas pouring into the motor and good oil. I am feed up with these carbs and will do what ever to get them to stop pouring gas into my motor